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I have a new build Gen 3 LQ6.0 with a 24X reluctor, black Gen 3 cam sensor, flashed for use 0411 ECM. I've used an American Auto Wire harness for the entire car except the GM harness. I have a Tremec 6 speed however no neutral safety switch wired in the AAW harness. Ground wires at the engine block to frame. Battery grounded to frame. Frame to body. Have a Tanks in tank pump with corvette regulator. Fuel rails are full of fuel and have pressure as I opened the dead end rail cap to verify.
0411 ECM two pink wires attached to back side of ignition switch hot when at crank and hot when key on. Blue at 12V BAT on key switch, hot when key on and crank.
not attached from ECM --- Green with white stripe - Fuel relay, Green - Fan 1, Blue - Fan 2, Yellow - Tach, Brown with white stripe - Check Engine, Green with white stripe - speedometer, Green - OB2
Cranks super fast with a new, fully charged 800CCA battery but no start. No spark at plugs. Where to even start ?
When you say GM engine harness can you contact the supplier for tech assistance? NSS is not needed on the 5/6 speed LS swaps I've done.
I would run the main ground cable direct to the engine block.
Oh and by the way great looking install. 55 Chev?
Many even basic scanners will show RPM. If it shows Zero RPM during cranking then your crank sensor (or its wiring) is bad. Typical cranking value is 150 RPM.
Check for +12V on the injectors and the coils when cranking.
The coils have 4 wires. The outer two are Ground and +12V, generally black and red. The middle two are signal and signal ground.
I've seen the injectors or coils wired to the fuel pump relay; i.e. they only have power when the fuel pump is running.
Make sure you have the coil harness on the correct side. You have to sure you have the proper side on the coil harness on drivers side then the correct on passenger side or it will not start.
First thing you do is check codes to see if the computer shows anything. if VATS has not been tuned out it'll show that. VATS controls the fuel injectors.
Next is to check voltage & grounds at all essential points. Test light works but I prefer a multimeter.
White plugs on Coil Packs have a pink wire in them, check that for 12v with key on and key in start.
If you know how to read a schematic we can show you the factory ones and you can check stuff from there.
If you don't have the Fuel Relay control wire from the ECM connected I take it you have a different setup pushing fuel to the Engine.
I checked each coil at cylinders 3-5 and 4-8 A-B 8.5 VDC, A-C 8.7 VDC, A-D.12.43 VDC Coils 1 and 2 12.39 VDC on all A-B, A-C, A-D ?? thats strange to me. noid light fires after i release the key from start position.... strange. 11.48 VDC at cam sensor plug at back of block.
I'll pull the starter today and check voltage at the crank sensor. Thoughts on where else to look or check??
Partial voltage like that you may have a short in a wire.
I thought A-B and A-C were signal wires ? Do you know if those 8-9VDC are good? The odd are 1 and 2 coils reading 12.3 DVC on all three wires ?? What coil set are you believing to be shorted?? 3-7 , 4-8 ?? or coils 1 and 2??
Yea that's what I figured you were doing. So your low reference, or ground, will have a voltage because of just stuff back feeding. Sounds normal to me.
I would look at my post above and use it as a checklist.
D to A is the important one, and you have 12v there so that's good.
No spark with good input voltage points toward the control side of the circuit, the PCM fires the coils.
Fixed it!!!... the two orange wires 20and 57 PCM supply ( my joined blue ) dropping out at crank. Moved that wire to a constant 12V source and we have a running 6.0. The .630 lift cam, 10.25/1 piston LS6 Ported heads have its sounding GREAT.
05-06-2024, 02:24 PM
LQ 6.0 Gen 3 no start 
